Plastic caps are typically manufactured from polymeric materials converted in a thermoplastic injection molding process, which comprises melting the material in a regulated screw/barrel assembly and pushing the material into a multi-cavity mold in order to enable the material to be formed and cooled.
Operators in this field are confronted with the costs of the plastic materials used which increase proportionally with the cost of hydrocarbons.
The present invention aims to reduce the costs by proposing a cap for a bottle intended to contain a fluid, the cap comprising at least a sealing portion and a lateral portion intended to be fastened to the bottle, the sealing portion comprising along a direction substantially perpendicular to the lateral portion a first region formed of unfoamed plastic material, a second region formed of foamed plastic material and a third region formed of unfoamed plastic material, the second region being positioned between the first region and the third region.
Thus, the presence of the second region made of foamed plastic material makes it possible to achieve a sufficient cap thickness to ensure that the necessary stiffness is obtained, while limiting the amount of raw materials used. A reduction in the weight of the caps then enables the reduction of the costs while retaining the functional, physical and chemical properties of the caps.
The expression “unfoamed plastic material” is understood in the present document to mean a solid plastic material corresponding to “unfoamed plastic material” or “plain material”.
Furthermore, the first and third regions formed of unfoamed plastic material correspond to what is sometimes referred to as “the skin” and the second region formed of foamed plastic material is sometimes referred to as the “foamed core”.